There have been few studies to date describing fatigue-crack propagation thresholds under mixed-mode loading conditions in the presence of cracks, that are small as compared to the characteristic microstructural dimensions. To address this need, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size is reported for a Ti-6Al-4V turbine blade alloy with a fine-gra...

Collapse by buckling a quite common phenomenon in sheets under pressure. When these structures caused by defects such as corrosion and cracks the time of the occurrence of this phenomenon is sensitive and critical load to be significantly reduced. Therefore, in this article sheet of aluminum Al 1200 by cracks in a part of the sheet will be considered. Left angle on the critical buckling load ef...

The size and length effects of an inclusion on multi-pass copper shaped-wire drawing were investigated. For this purpose, an experimental investigation on optimal die half-angle was conducted. Based on experimental data of optimal die half-angle, wire and inclusion deformations, drawing and hydrostatic stress of copper shaped-wires that contain an inclusion were calculated by two-dimensional fi...

In this paper, we construct a model for prediction of fatigue crack initiation based on the material’s microstructure. In order to do so, the energy of a persistent slip band (PSB) is monitored and an energy balance approach is taken, in which cracks initiate and the material fails due to stress concentration from a PSB (with respect to dislocation motion). These PSBs are able to traverse low-a...

hydraulic fracturing (hf), as a stimulation technique in petroleum engineering, has made possible the oil production from reservoirs with very low permeability. the combination of horizontal drilling and multiple hf with various perforation angles has been widely used to stimulate oil reservoirs for economical productions. despite the wide use of hf, there are still ambiguous aspects that requi...

Helical gears are commonly used in industry as they have advantages of higher power density, quieter operation etc., compared to spur gears. Conventional gear design is based on various design criteria, including durability and bending strength load rating. In recent times, fracture failure modes are gaining importance in addition to conventional failure modes. Stresses due to operating fatigue...

Highly enhanced adhesion can be achieved between surfaces patterned with complementary micro-channel structures. An elastic material, poly(dimethylsiloxane) (PDMS), is used to fabricate such surfaces by molding into a silicon master with micro-channel profi les patterned by photolithography. For each pair of complementary surfaces, dislocation defects are observed in the form of visible striati...

Mixed-mode, high-cycle fatigue-crack growth thresholds are reported for through-thickness cracks (large compared to microstructural dimensions) in a Ti±6Al±4V turbine blade alloy with a bimodal microstructure. Speci®cally, the e€ect of combined mode I and mode II loading, over a range of phase angles b ˆ tanÿ1…DKII=DKI† from 0° to 82° …DKII=DKI 0±7), is examined for load ratios (ratio of minimu...

This paper deals with the determination of the effect of varying material properties on the value of the stress intensity factors, KI and KII, for anisotropic plates containing cracks and subjected to a temperature change. Problems involving cracks and body forces, as well as thermal loads are analysed. The quadratic isoperimetric element formulation is utilized, and SIFs may be directly obtain...